RESUMO
In recent years, natural alternatives have been sought for the control of beekeeping pathologies; in the case of American Foulbrood (AFB) disease, the use of synthetic antibiotics was prohibited due to honey contamination and the generation of resistant bacteria. The significant increase in population growth worldwide has led to great concern about the production of large amounts of waste, including those from agribusiness. Among the most important beverages consumed is coffee, generating thousands of tons of waste called spent coffee grounds (SCG). The SCG is a source of many bioactive compounds with known antimicrobial activity. The aims of the present work were: (1) to obtain and chemically analyse by HPLC of SCG extracts (SCGE), (2) to analyse the antimicrobial activity of SCGE against vegetative form of Paenibacillus larvae (the causal agent of AFB), (3) to evaluate the toxicity in bees of SCGE and (4) to analyse the effect of the extracts on the expression of various genes of the immune system of bees. SCGs have a high content of phenolic compounds, and the caffeine concentration was of 0.3%. The MIC value obtained was 166.667 µg/mL; the extract was not toxic to bees, and interestingly, overexpression of abaecin and hymenoptaecin peptides was observed. Thus, SCGE represents a promising alternative for application in the control of American Foulbrood and as a possible dietary supplement to strengthen the immune system of honeybees. Therefore, the concept of circular bio-economy could be applied from the coffee industry to the beekeeping industry.
Assuntos
Paenibacillus larvae , Abelhas , Animais , Café , Peptídeos Antimicrobianos , Antibacterianos/farmacologia , LarvaRESUMO
In the present work, the provenance discrimination of Argentinian honeys was used as case study to compare the capabilities of three spectroscopic techniques as fast screening platforms for honey authentication purposes. Multifloral honeys were collected among three main honey-producing regions of Argentina over four harvesting seasons. Each sample was fingerprinted by FT-MIR, NIR and FT-Raman spectroscopy. The spectroscopic platforms were compared on the basis of the classification performance achieved under a supervised chemometric approach. Furthermore, low- mid- and high-level data fusion were attempted in order to enhance the classification results. Finally, the best-performing solution underwent to SIMCA modelling with the purpose of reproducing a food authentication scenario. All the developed classification models underwent to a "year-by-year" validation strategy, enabling a sound assessment of their long-term robustness and excluding any issue of model overfitting. Excellent classification scores were achieved by all the technologies and nearly perfect classification was provided by FT-MIR. All the data fusion strategies provided satisfying outcomes, with the mid- and high-level approaches outperforming the low-level data fusion. However, no significant advantage over the FT-MIR alone was obtained. SIMCA modelling of FT-MIR data produced highly sensitive and specific models and an overall prediction ability improvement was achieved when more harvesting seasons were used for the model calibration (86.7% sensitivity and 91.1% specificity). The results obtained in the present work suggested the major potential of FT-MIR for fingerprinting-based honey authentication and demonstrated that accuracy levels that may be commercially useful can be reached. On the other hand, the combination of multiple vibrational spectroscopic fingerprints represents a choice that should be carefully evaluated from a cost/benefit standpoint within the industrial context.
RESUMO
This study aimed to characterize the chemical composition of Aloysia polystachia, Acantholippia seriphioides, Schinus molle, Solidago chilensis, Lippia turbinata, Minthostachys mollis, Buddleja globosa, and Baccharis latifolia essential oils (EOs), and to evaluate their antibacterial activities and their capacity to provoke membrane disruption in Paenibacillus larvae, the bacteria that causes the American Foulbrood (AFB) disease on honey bee larvae. The relationship between the composition of the EOs and these activities on P. larvae was also analyzed. Monoterpenes were the most abundant compounds in all EOs. All EOs showed antimicrobial activity against P. larvae and disrupted the cell wall and cytoplasmic membrane of P. larvae provoking the leakage of cytoplasmic constituents (with the exception of B. latifolia EO). While, the EOs' antimicrobial activity was correlated most strongly to the content of pulegone, carvone, (Z)-ß-ocimene, δ-cadinene, camphene, terpinen-4-ol, elemol, ß-pinene, ß-elemene, γ-cadinene, α-terpineol, and bornyl acetate; the volatiles that better explained the membrane disruption were carvone, limonene, cis-carvone oxide, pentadecane, trans-carvyl acetate, trans-carvone oxide, trans-limonene oxide, artemisia ketone, trans-carveol, thymol, and γ-terpinene (positively correlated) and biciclogermacrene, δ-2-carene, verbenol, α-pinene, and α-thujene (negatively correlated). The studied EOs are proposed as natural alternative means of control for the AFB disease.